Communication among computing devices typically occurs through networks. For computing devices in a wired network to communicate, each device must have a unique network identifier. In packet-switched networks, each network device is assigned an internet protocol (IP) address to identify the particular device in the network.
The dominant standard for IP addresses is internet protocol version four (IPv4). IPv4 addresses are 32 bits in length, which limits the possible number of IPv4 addresses available for use to 4,294,967,296 (2^32). As the number of client devices seeking network connections continues to grow, the number of available IPv4 addresses continues to decline and will eventually reach zero. This problem is known as IPv4 address exhaustion. Although estimates of the approximate date of IPv4 address exhaustion vary, it is widely recognized that IPv4 addresses will eventually be exhausted.